This invention relates to fibre optic apparatus which is primarily, although not exclusively, suited for use in security and communication applications.
The specification of South African Pat. No. 78/5419 describes a security system in which a length of optic fibre is permanently located at the boundary of a given area. Undue movement or breakage of the optic fibre, which may be caused for example by an intruder, produces variations, which includes complete cessation, in the intensity of an optical signal in the optic fibre which may be detected to signify a security breach. Similar installations are disclosed in the specifications of German Pat. No. 2714241 and U.K. Pat. No. 1,497,995. Security systems of this type suffer from the disadvantage that they are by nature permanent installations.